1. Field of the Invention
This invention relates to molding resins and more specifically it relates to molding resins based on acid copolymer/hydrocarbon polyolefin/reinforcing fiber blends modified by the addition of wetting agents.
2. Description of the Prior Art
U.S. Pat. No. 3,639,331, "Glass Fiber Reinforced Resins Containing Dispersion Aid" discloses improved glass dispersibility in a thermoplastic resin at glass concentrations ranging from 20-90 weight % using as the dispersing aid a hydrocarbon lubricant, or a plasticizer or a low molecular weight resin at concentrations ranging from 0.5 to 8.0 weight %. This patent primarily refers to low molecular weight oils and plasticizer as dispersing aids using an 80% by weight glass concentrate and blending this with unreinforced polymer to give a final product having 20% glass fiber content. This two step blending process shows no significant improvement in physical properties.
U.S. Pat. No. 3,640,943, "Polymer-Filler Composition", discloses a composition comprising a base polymer, a filler and a surface-active additive which is a block copolymer (polydiphenyl siloxane-polydimethylsiloxane). The block copolymer additive contains at least two polymerized comonomers, one of which is compatible with the base polymer thereby imparting stability to the composition and the second of which is surface active in the composition so that the block copolymer is concentrated at the interface between the filler and base polymer to provide a bond therebetween. Although this patent claims improved stiffness and greater dimensional stability, other physical properties were not significantly improved.
In neither one of the above patents is there any disclosure of blends based on ionomers nor of the use of simple wetting agents to give improved physical properties at high filler loadings in hydrophobic polymer systems.
U.S. Pat. No. 3,856,724 discloses reinforced thermoplastic compositions based upon a reinforcing agent such as glass fiber or alpha cellulose with a polyolefin such as polyethylene, polypropylene, polyisobutylene, etc. and a minor amount of an ionic hydrocarbon copolymer, such as an ethylene-methacrylic acid copolymer which has been reacted with an ionizable metal compound. It is disclosed that generally, the amount of the ionic hydrocarbon copolymer will be from about 0.05 to about 35 percent by weight and, preferably, from about 1 to about 30 percent by weight based on the weight of the reinforced thermoplastic composition.
Copending patent application Ser. No. 236,718 filed Feb. 23, 1981, now U.S. Pat. No. 4,387,188 (Attorney Docket No. AD-5095) discloses compositions of about 38 to 90% by weight of acid copolymer (from 0 to about 90% neutralized), about 5-60% by weight of linear polymer of .alpha.-olefin and about 2-50% by weight of reinforcing fiber.